KR0178821B1 - Variable valve operating system for engine - Google Patents

Abstract

In the variable dynamic valve device of an engine, the main rocker arm 1 follows the low speed cam 21 related to opening and closing of the valve during low speed operation by providing a profile function in the case of a poor switching operation of the cam. Simultaneously the limit rotational speed N _{2 followed by the} sub-locker arm 2 and the main rocker arm 1 with respect to the limit fire water N ₁ and the high speed cam 22 related to opening and closing of the valve during high speed operation. Set above the maximum speed in the commercial area of the engine.

Description

Variable valve device of engine

1 is a plan view of a movable valve system showing an embodiment of the present invention.

2 is a cross-sectional view taken along the X-X line of FIG.

3 is a cross-sectional view taken along the line Y-Y of FIG.

4 is a cross-sectional view taken along the line Z-Z of FIG.

5 is a graph showing valve lifts, accelerations, and the like.

6 is a graph showing the valve lift.

7 is a table showing an example of setting the opening valve angle, the valve lift, and the limited rotation speed.

8 is a graph showing the output characteristics of an engine.

* Explanation of symbols for main parts of the drawings

1: main rocker arm 2: sub rocker arm

9: intake valve 21: low speed cam

22: High Speed Cam 25: Lost Motion

33,34: flanger 41: oil passage

The present invention relates to an improvement of a variable dynamic valve device for switching valve lift (lifting) characteristics at low and high rotational speeds of an engine.

[Prior art]

Conventionally, for the purpose of achieving both torque during low and medium speed movements and output improvement during high speed operation, the lift characteristics of the intake valves or exhaust valves are changed depending on the operating state, and thereby the timing of the intake / exhaust valves and the intake / exhaust amount are controlled. Known.

As a variable dynamic valve device of this kind, there is one disclosed in Japanese Patent Laid-Open No. 2-42107, for example.

Explaining this, the low speed rocker arm whose swinging end abuts against the valve and the high speed rocker arm which does not have a part which abuts with the valve adjacent to one side of this low speed rocker arm are made to rock | swivel to a common rocker shaft. The low-speed cam is supported by the low-speed rocker arm, and the high-speed cam is in sliding contact with the high-speed rocker arm, which has a profile in which an open valve angle or a valve lift (maximum lift amount of the valve) is larger than that of the low-speed cam.

Furthermore, in rocking portions at predetermined distances away from the rocker shaft, two rocker arms are connected or disconnected by the flanger moving out of the engagement hole in the direction parallel to the rocker shaft.

When the high speed cam is in high speed operation related to opening / closing of the valve, the low speed rocker arm oscillates integrally with the high speed rocker arm, and the low speed cam floats on the low speed rocker arm and revolves. The limit rotation speed to be followed is set lower than the limit rotation speed following the high speed rocker arm in the high speed cam.

[Problems to Solve Invention]

However, due to a malfunction of a valve or the like that controls the hydraulic pressure acting on the full ranger, the low speed cam may be involved in opening and closing the valve during high speed operation. It may not be followed, may cause a decrease in durability of the movable valve system, and a problem that noise occurs between the low speed rocker arm and the speed cam may be considered.

In view of the above problems, an object of the present invention is to have a fail safe (double safe device) function in a cam changeover operation of an engine.

[Means for solving the problem]

The present invention has a plurality of cams for a common intake valve or exhaust valve including a low speed cam and a high speed cam having at least one of a valve lift or an open valve angle larger than that of the low speed cam. In a variable dynamic valve apparatus of an engine having a cam converter mechanism for converting a cam related to a driving condition according to operating conditions, the maximum rotational speed in a commercial area of the engine together with the limit rotational speed of a portion following the cam movement. That's it.

[Action]

For example, high-speed cam to be related to the cam switching mechanism to the rotation limit that follows (N ₁₎ is gusong the like rocker arm against the low-speed cam to be related to the opening and closing of the valve, the opening and closing of the valve during high-speed operation at the time of low speed operation By setting the engine speed beyond the maximum rotation speed in the commercial area of the engine together with the limit rotation speed (N) followed by the cam switching mechanism, if a malfunction occurs in the control system and the opening and closing of the low speed cam is performed until the high speed operation. By following the main rocker arm with respect to the cam surface of the low speed cam until high speed operation, noise can be prevented from occurring between the rocker arm and the low speed cam, and a secondary failure can be avoided.

EXAMPLE

EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described based on an accompanying drawing.

1, 2 and 3 show a multi-cylinder engine equipped with two valves (any of intake valves and exhaust valves, which may be referred to as intake valves) having the same function for one cylinder. The example in the case where this invention is applied is shown.

Explaining this, each cylinder is provided with a single main rocker arm 1 corresponding to the two intake valves 9. The base end of the main rocker arm 1 is freely supported by the cylinder through the main rocker shaft 3 common to each cylinder, and the stem of the intake valve 9 (top part) is provided at the tip of the main rocker arm 1. ), The adjusting screw 10 is fastened through the nut 11.

The roller 14 is rotatably connected to the main rocker arm 1 via the needle bearing 12 to the shaft 13, and is configured to bring the low speed cam 21 into rolling contact with the roller 14.

The main rocker arm 1 is formed in a substantially rectangular shape in plan view, and the main rocker arm 1 is provided with a single sub rocker arm 2 parallel to the roller 14. The base end of this sub rocker arm 2 is rotatably connected relative to the main rocker arm 2 via the sub rocker shaft 16. The sub-locker shaft 16 is slidably engaged with the hole 17 formed in the sub-rocker arm 2, and is pressed into the life 18 formed in each main rocker arm 1.

The sub-locker arm 2 does not have a portion that is in contact with the intake valve 9, and a cam follower portion 23 in sliding contact with the high speed cam 22 is formed at an end thereof so as to protrude in an arc shape. The lost motion spring 25 which attaches the follower part 23 to the high speed cam 22 is attached.

The main rocker arm 1 is formed under the sub rocker arm 2 and is formed integrally with a circumferential recess 26 to which the lost motion spring 25 is mounted. The lower end of the coil-shaped lost motion spring 25 is placed on the bottom face 26a of the recess 26 and the upper end thereof is through the retainer 27 which is freely engaged with the recess 26. Abutted with the follower part 28 formed integrally with

As shown in FIG. 4, in order to stop the relative rotation of both rocker arms 1 and 2 with each other, the sub rocker arm 2 is provided with the hole 32 which slides and engages the flanger 31 freely. The main rocker arm 1 is formed with holes 35 and 36 for slidingly engaging the flangers 33 and 34, respectively, and an oil chamber 37 is formed behind the flanger 33. The return spring 38 is mounted behind the flanger 34.

A stopper 39 is pressed into one of the holes 36 engaged with the flanger 34, and the stopper 39 is provided with a hole 40 through which air is drawn out.

An oil passage 41 for supplying hydraulic pressure to the oil chamber 37 is provided through the interior of the main rocker arm 1 and the main rocker shaft 3. The main rocker arm 1 is provided with a through-hole 43 through which one of the openings in the oil chamber 37 and the other through the bearing surface 42 against the main rocker shaft 3 is formed. On one side of 43), the stopper 45 is pressed. An oil gallery 44 is formed axially in the rocker shaft 3, and the main rocker arm 1 is formed through the through-hole 46 and the annular groove in the oil gallery 44. It communicates with the through hole 43 of.

In the oil gallery 44, the discharge oil pressure of the oil pump is guided at a predetermined high speed operation through a switching valve (not shown). The control unit for electronically controlling the operation of the switching valve inputs an engine rotation signal, a cooling water temperature signal, a lubricating oil temperature signal, a supercharge pressure signal of the intake air by the supercharger, an opening degree signal of the throttle valve, and the like, based on these detected values. In this way, it is possible to smoothly switch between the low speed cam 21 and the high speed cam 22, which will be described later, while suppressing sudden fluctuations in the engine torque.

The low speed cam 21 and the high speed cam 22 adjacent to each other are integrally formed on a common cam shaft, and have different shapes (different sizes) to satisfy the valve lift characteristics required at low and high rotational speeds of the engine. Different forms are also included). In other words, the high speed cam 22 has a profile that enlarges at least one of the valve lift or the open valve angle (opening valve period) as compared to the low speed cam 21. Here, the valve lift and the open valve angle are increased at the same time.

During low speed operation of the engine, the main rocker arm 1 swings in accordance with the profile of the low speed cam 21, and opens and closes each intake valve 9. At this time, the sub-locker arm 2 is swung by the high speed cam 22, but as shown in FIG. 4A, the flanger arms 33, 31, and 34 are driven by the biasing force of the return spring 38. As shown in FIG. ) Enters into each of the holes 35, 32, 36 respectively, and does not restrain the swing of the main rocker arm 1.

On the other hand, when operating hydraulic pressure is guided to the oil chamber 37 through the oil gallery 44 and the oil passage 41 at the time of high-speed operation of an engine, as shown in FIG. 4 (b), each plan The reservoirs 33, 31 and 34 move against the return spring 38, the flanger 33 moves to each of the holes 35 and 32, and the flanger 34 moves to each hole 32. And 36), the two rocker arms 1, 2 are united and oscillated by being engaged. Here, since the high speed cam is formed such that the opening angle and the lift amount of the valve are larger at the same time than the low speed cam, the roller 14 of the main rocker arm 1 during swinging integrated with the sub-locker arm 2 is formed. Is raised by the low speed cam 21, and each of the intake valves 9 is opened and closed by the high speed cam 22 in accordance with the profile, and the opening angle and the lift amount of the valve are simultaneously increased.

On the other hand, when the engine moves from the high rotational region back to the low rotational region, the oil rock guided to the oil chamber 37 is lowered by the operation of the switching valve, and each flanger 33 by the elastic restoring force of the return spring 38 is reduced. 31. 34 is moved to its original position and the lock on the aim locker arm 1 is released.

Therefore, although the gist of the present invention, the limit rotational speed (N ₁ , N ₂ ) that the main rocker arm (1) and the sub rocker arm (2) follows the low speed cam (21) and high speed cam (22), respectively. Is set at about the same time so as to be equal to or greater than the maximum rotation speed in the commercial area of the engine at the same time.

In this engine, the supply of fuel is stopped when a predetermined fuel cut conversion water (N ₄ ) is reached, and further increase in rotation is regulated. However, in this embodiment, the maximum rotation speed in the commercial area of the engine is regulated. Is set to the fuel cut rotation speed N ₄ , and each said limit rotation speed N ₁ and N ₂ is set to the fuel cut rotation speed N ₄ or more simultaneously.

In the high speed cam operation in which the main rocker arm 1 is integrated with the sub rocker arm 2 and swings, the limit rotation speed at which the sub rocker arm 2 is in sliding contact with the cam surface of the high speed cam 22 does not fall. (N ₂ ) can be roughly calculated as follows.

However, m ₂ is a valve side equivalent inertia mass (kg) at the time of a high speed cam operation | movement, and is computed by following Formula.

mv is the mass (kg) of the intake valve 9, mr is the mass (kg) of the retainer 7 and the coater (not shown) attached to the intake valve 9, ms is the mass of the valve spring 8 It is mass (kg).

Ir ₂ is the moment of inertia (kg, mm 2) with respect to the main rocker shaft 3 of the rocker arm 1 in which the sub rocker arms 2 are integrated.

b is the distance (mm) between the center of the main rocker shaft 3 and the centerline of the intake valve 9.

F ₂ is a spring load N applied by the valve spring 8 to the intake valve 9.

As shown in FIG. 5, y2max is the maximum speed (mm / rad ² ) of the intake valve 9 following the high speed cam 22.

In the low speed cam operation in which the main rocker arm 1 oscillates independently of the sub rocker arm 2, the limit rotation speed at which the main rocker arm 1 is in sliding contact with the cam surface of the low speed cam 21 does not fall. N ₁ ) can be roughly calculated by the following equation.

However, m ₁ is the valve side equivalent inertial mass at the time of low speed cam operation | movement, and is computed by following Formula.

Ir ₁ is the moment of inertia (kg, mm 2) with respect to the main rocker shaft 3 of the rocker arm 2 to which the sub rocker arm 2 swings independently. That is, it is equal to the moment of inertia (kg, mm 2) except for the sub-locker arm 2, the lost motion spring 25, and the lift 26.

c is the distance (mm) between the center of the main rocker shaft 3 and the centerline of the lift 26.

f is the spring load N which the lost motion spring 25 gives to the sub rocker arm 2. As shown in FIG.

y1max is the maximum added speed (mm / rad ² ) of the intake valve 9 following the low speed cam 21.

In the low speed cam operation in which the main rocker arm 1 swings independently of the sub rocker arm 2, the sub rocker arm 2 does not fall against the cam surface of the high speed cam 22. The limit rotation speed N ' _{1 in} sliding contact can be roughly calculated by the following equation.

However, m ₃ is almost equal to the sum (kg) of the mass of the movable portion of the sub-locker arm 2, the mass of the lift 26 and the mass of the lost motion spring 25 multiplied by 1/3.

y3max is the maximum load speed (mm / rad ² ) of the cam lift curve of the high speed cam 22.

Thus, for the low speed cam 21 and to high-speed cam 22, the main rocker arm 1 and sub-rocker arm 2 is substantially equal to the number of limit rotation that follows each _{for, N 2 ≒ N 1 ≒ N} 1 ' Set in relation to.

By the way, conventionally, as shown by the solid line in FIG. 6, since the low-speed cam 21 is set to a smaller width than the high-speed cam 22, the maximum additional speed | y1max | is | y2max. is a value greater than │, the limit number of revolutions N ₁ no special sense to be larger than the N _2, is a value less than N _2. Specifically, as shown in the table of FIG. 7, the high speed cam 22 has a limit in which the opening valve angle is set to 280 ° and the valve lift is set to 1 mm, and the intake valve 9 follows the high speed cam 22. While the rotational speed N ₂ becomes 9000 rpm, the low speed cam in the conventional apparatus has an opening valve angle of 220 ° and a valve lift of 8 mm, and the limit rotational speed at which the intake valve 9 follows the low speed cam. (N ₁ ) becomes 7000 rpm.

As one means to cope with this, as shown by the dotted line in FIG. 6, the opening valve angle of the low speed cam 21 is set relatively large.

As another means to cope with this, as shown by the dashed-dotted line in FIG. 6, the valve lift of the low speed cam 21 is set relatively small.

6 also shows lift characteristics of the low speed cam and the high speed cam for opening and closing the exhaust valve.

Specifically, as shown in the table of FIG. 7, in the first embodiment, the open valve angle of the low speed cam 21 is set to 250 ° and the valve lift is set to 8 mm, and the intake valve 9 is set to the low speed cam ( The limit rotational speed N ₁ following 21) is 9400 rpm.

As a second embodiment, the limiting rotation speed N ₁ at which the open valve angle of the low speed cam 21 is set to 220 ° and the valve spring is set to 6 mm, and the intake valve 9 follows the low speed cam 21 is 9200 rpm.

In this way, the limit rotation speed N that the sub-locker arm 2 follows the high speed cam 22 with respect to the low speed cam 21 with respect to the high speed cam 22 with the limit rotation speed N _{1 followed} by the main rocker arm 1. ₂ ) at the same time, if an operation failure such as a switching valve for controlling the hydraulic pressure occurs, and the low speed cam 21 continues to open and close the intake valve 9 until a high speed operation is performed in some cylinders, the low speed cam ( Follows the main rocker arm 1 with respect to the cam surface of 21), prevents noise from occurring between the main rocker arm 1 and the low speed cam 21, and causes a secondary failure in its movable valve system. Can be avoided.

In addition, the high speed cam 22, the sub-locker arm (2) with respect to the high speed cam 22, the limit rotational speed (N ₁ ') that the sub-locker arm (2) follows through the lost motion spring (25). By setting equal to the limiting revolution speed N ₂ to be followed, if an operation failure such as a switching valve for controlling hydraulic pressure occurs, and the low speed cam 21 is related to opening and closing of the intake valve 9 during high speed operation, The sub rocker arm 2 is followed by the cam surface of the high speed cam 22, so that noise can be prevented between the sub rocker arm 2 and the high speed cam 22.

FIG. 8 shows the output power characteristic of the engine. However, in the first embodiment, the opening valve angle of the low speed cam 21 is set relatively large, so that the output at low speed operation is slightly lowered, but at high speed operation. The output rises and the generation output is suppressed from dropping suddenly in the rotational speed range that switches from the low speed cam 21 to the high speed cam 22. In the case of the second embodiment, by setting the valve lift of the low speed cam 21 relatively small, the generation output during the low speed operation rises on the contrary.

In addition, the switching mechanism which switches the cam which concerns on opening / closing operation | movement of a valve is not limited to the structure provided with the circumferential flanger 33 and 34 like the said Example.

[Effects of the Invention]

As described above, the present invention provides a variable dynamic valve apparatus of an engine including a cam having a restoring cam profile different from a normal intake valve or an exhaust valve, and having a cam switching mechanism for switching a cam related to opening / closing operation of the valve. In this case, the limit rotational speed that the cam switching mechanism follows for each cam is set at the same time as the maximum rotational speed or more in the commercial area of the engine. When the low speed cam to be used is related to opening and closing of the valve, the main rocker arm follows the cam of the low speed cam until the high speed operation prevents noise from occurring between the rocker arm and the low speed cam, A secondary fault can be avoided in the system.

Claims (1)

A common intake valve or exhaust valve is provided with a plurality of cams including a high speed cam in which at least one of a valve lift or an open valve angle is set larger than that of the low speed cam and the low speed cam. In a variable dynamic valve apparatus of an engine having a cam converter mechanism for converting a cam in accordance with operating conditions, the limit rotational speed of a portion moving following each cam is set to be equal to or higher than the maximum rotational speed in the commercial area of the engine. The variable dynamic valve device of the engine, characterized in that.